Needle counter device

ABSTRACT

A needle counter device which includes a latch mechanism for securing the device in a closed condition. The latch mechanism preferably consists of a latch member which is integrated into the edge of a lid of the device and which is configured to be received in a corresponding hole or aperture in a base of the device, as this arrangement simplifies manufacturing, as well as increases resistance to deflection and spreads the opening load (i.e., the load used to unlatch the latch mechanism) into a whole side of the part instead of having the load be concentrated at a narrow portion. This latch mechanism can be implemented in connection with a needle counter device as described above, wherein the needle counter device utilizes an adhesive disposed in one or more troughs. Alternatively, the latch mechanism can be implemented in connection with a more conventional needle counter device, such as one which does not include an adhesive disposed in one or more troughs.

RELATED APPLICATION (PRIORITY CLAIM)

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/010,067, filed Dec. 10, 2004, which claims the benefit ofU.S. Provisional Application Ser. No. 60/556,678, filed Mar. 26, 2004,both of which are hereby incorporated by reference in their entirety.

BACKGROUND

The present invention generally relates to needle counter devices usedin surgery, and more specifically relates to a needle counter devicewhich includes an adhesive disposed in one or more troughs for receivingand retaining sharps (i.e., needles, blades, etc.) during surgery.

It is important to account for and safely retain for disposal, allsuture needles used in a surgical procedure. Since the quantity ofneedles used for any given surgical procedure can vary widely, severalneedles may need to be accounted for and each must be accounted for toassure none is left in the patient or in the surgical drapes, bed sheetsor lost elsewhere. This protects the patient, the surgical and nursingstaff as well as cleaning and laundry personnel. Scalpel blades may alsobe retired or changed out during procedures and thus become a hazardunless they too are accounted for. The potential for presence of bloodborn pathogens on these contaminated sharp objects makes theirsafekeeping essential so they can be disposed of at minimal risk.

Numerous needle counting device concepts already exist. Methods used toretain the sharps include use of soft penetrable foam strips, magneticsheets, thin film adhesives, foam backed film adhesives, “piggy bank”type receiving slots and various combinations of these items. Many ofthese devices date back more than 30 years. Many of the devices arecontained within a variation of a hinged plastic box form that opens andcloses like a book. Various methods have been employed to latch or lockthe box closed. Often the sharps receiving section of the needle counteris divided into numbered sections for needle placement in order tofacilitate the counting process. From the user standpoint, improvedmeans to assure and facilitate accurate counting of these needles andprevent accidental dislodgement has become more important in recentyears, especially as the average age and general shortage of nursingstaff means that the declining quality of the users eyesight and theirneed to be more efficient come into conflict.

Some examples of prior art devices can be found in U.S. Pat. No.3,944,069 (Pressure sensitive adhesive coated foam pad); U.S. Pat. No.4,008,802 (Resilient pad with raised ridges for receiving needles); U.S.Pat. No. 4,013,109 (Hinged container with magnetic surface to holdneedles); U.S. Pat. No. 4,243,140 (Hinged container with slotted foamribs on one side and a thin adhesive layer on the other to hold sharps);and U.S. Pat. No. 4,596,329 (Combinations of foam and magnetic media toretain sharps).

Needle counters are very much a commodity item in the health care fieldand as such must be made inexpensively and sold cheaply in order tocompete. Recent OSHA emphasis and legislation directed toward safehandling methods and systems for contaminated sharps to prevent transferof diseases by blood born pathogens has directed more attention uponuser friendliness and ease of use of these devices. Soft foam padsrequire that the often curved suture needles be impaled into or throughthem. Some foam pads are slotted to receive the needles within theirslots. Magnetic sheets are sometimes used to hold the needles. Somehybrid concepts have a thin adhesive film applied to a foam pad whereinthe pad may be impaled with the needle or the needle or sharp may beretained by the adhesive on contact.

All these devices do their job with varying degrees of success: 1) Thefoam devices generally provide very little grip and often fail to retainneedles against very low dislodging forces unless they are made of anelastomeric foam and then they require a rather high insertion force inorder to deliver a high pull-out force. 2) Magnets hold the low carbonstainless needles with some degree of success but the needles typicallydislodge very easily and can be pushed around and disorganized orknocked loose if even slightly disturbed. Occasionally the sharps canbecome magnetized from contact with the magnetic sheet whereupon theymay tend to move from their assigned location and clump together whichmakes counting difficult, especially when very fine needles areinvolved. Some surgeons complain that the magnetized needles tend toattract to the needle holder forceps and become difficult to handle.Magnetic sheets are also costly and they are generally dark in color sothey fail to provide good visual contrast for observing the shiny metalneedles. 3) Thin film adhesive surfaces are not very compliant andtherefore limited in effectiveness by the amount of surface area of thesharps they can attach to. Backing thin film adhesives with a foam padhelps assist in utilization of the adhesive but remain far from an idealsolution since the film membrane also tends to inhibit insertion ofneedles into the foam. Many devices have also employed an adhesive ontheir bottom in order to secure the device to a work surface and preventmovement during use.

OBJECTS AND SUMMARY

An object of an embodiment of the present invention is to provide aneedle counter device which is configured to hold a needle fast witheither minimal insertion force or simple incidental contact in order tomake certain the needle remains at the location it was assigned by ahealthcare worker.

Another object of an embodiment of the present invention is to provide aneedle counter device which facilitates good illumination of placedneedles to assure easy visibility for placement and counting at the endof the procedure.

Still another object of an embodiment of the present invention is toprovide a needle counter device which is configured such that needlesremain upright where they are placed and viewing them is not hampered bythe background color of the retaining media.

Yet another object of an embodiment of the present invention is toprovide a needle counter device which has easy to read numericalindicia.

Still yet another object of an embodiment of the present invention is toprovide a needle counter device which is: very inexpensive tomanufacture, constructed of very few parts, capable of being assembledin few steps, and designed such that it facilitates an automatedprocess.

Briefly, and in accordance with at least one of the foregoing objects,an embodiment of the present invention provides a needle counter devicewhich utilizes an adhesive disposed in one or more troughs. Although thetroughs may be provided in many different cross-sectional shapes,preferably the troughs are V-shaped to conserve the amount of adhesivewhich must be provided to fill the troughs. The adhesive providesinstant, strong grip upon contact, but also provides very low resistanceto needle penetration. In other words, it is easy to sink a needle inthe adhesive, but difficult to pull the needle out of the adhesive. Theadhesive may be a synthetic polymer “hot melt” adhesive which quicklyconforms to the needle surface and, due to its low durometer, displaysremarkable adhesion to even very fine needles delivered with a forceequal to no more than the needle's own weight. Preferably, properties ofthe adhesive are such that tugging upon an applied needle tends to causethe adhesive to elongate at the attachment or “pull legs” in such amanner that the needle, when released, is elastically withdrawn back tothe adhesive surface.

Preferably, the adhesive is thicker than that of the common film type,and is injected into the trough(s), such that the aspect ratio of theapplied adhesive is more like that of a bead than that of a film. Theadhesive material may be applied in a manner such that it visibly risesabove the housing surface to present a good thick target for eitherinserting the needle or simply laying it against the tacky surface. Outof economic necessity, preferably the device is designed for ease ofmanufacture and assembly in order to facilitate automated construction.

Preferably, the device includes a latch mechanism for securing thedevice in a closed condition. The latch mechanism preferably consists ofa latch member which is integrated into the edge of a lid of the deviceand which is configured to be received in a corresponding hole oraperture in a base of the device, as this arrangement simplifiesmanufacturing, as well as increases resistance to deflection and spreadsthe opening load (i.e., the load used to unlatch the latch mechanism)into a whole side of the part instead of having the load be concentratedat a narrow portion. This latch mechanism can be implemented inconnection with a needle counter device as described above, wherein theneedle counter device utilizes an adhesive disposed in one or moretroughs. Alternatively, the latch mechanism can be implemented inconnection with a more conventional needle counter device, such as onewhich does not include an adhesive disposed in one or more troughs.

BRIEF DESCRIPTION OF THE DRAWINGS

The organization and manner of the structure and operation of theinvention, together with further objects and advantages thereof, maybest be understood by reference to the following description, taken inconnection with the accompanying drawings, wherein:

FIG. 1 is a top perspective view of a needle counter device which is inaccordance with a preferred embodiment of the present invention, showingthe device partially open;

FIG. 2 is bottom perspective view of the needle counter device shown inFIG. 1, showing the device partially open;

FIG. 3 is a view similar to FIG. 1, but showing the device in transversesection;

FIG. 4 is a view similar to FIG. 1, but showing a base of the device inlongitudinal section;

FIG. 5 is a view similar to FIG. 1, but showing a lid of the device inlongitudinal section;

FIG. 6 is a close up view of the needle counter device, showing aninserted needle at location 1 and a laid down needle at location 11;

FIGS. 7 and 8 illustrate a range of needle types offered by a vendor inthe marketplace;

FIG. 9 illustrates a needle counter device which is in accordance withan alternative embodiment of the present invention, wherein a large foampad with holes is provided on the inside surface of the lid;

FIG. 10 is a top, perspective view of a needle counter device (in anopen condition) which is in accordance with yet another embodiment ofthe present invention, wherein the device includes an improved latchmechanism;

FIG. 11 is a view of the needle counter device of FIG. 10, showing thedevice in a closed condition;

FIG. 12 is a close up view of the latch mechanism of the needle counterdevice shown in FIGS. 10 and 11;

FIG. 13 is a cross-sectional view, taken along line 13-13 of FIG. 11, ofthe needle counter device shown in FIGS. 10 and 11;

FIG. 14 is a view very similar to FIG. 12, but at an angle so that theinside of the device can be seen; and

FIG. 15 is a cross-sectional view of one of the hinges of either one ofthe needle counter devices shown in the previous Figures.

DESCRIPTION OF ILLUSTRATED EMBODIMENTS

While the invention may be susceptible to embodiment in different forms,there are shown in the drawings, and herein will be described in detail,specific embodiments of the invention. The present disclosure is to beconsidered an example of the principles of the invention, and is notintended to limit the invention to that which is illustrated anddescribed herein.

FIGS. 1-6 illustrate a needle counter device 10 which is in accordancewith a preferred embodiment of the present invention. The needle counterdevice provides a mechanism that holds a needle fast with either minimalinsertion force or simple incidental contact in order to make certainthe needle remains at the location it was assigned by a healthcareworker. The needle counter device also facilitates good illumination ofplaced needles to assure easy visibility for placement and counting atthe end of the procedure. Further, the needle counter device providesthat needles remain upright where they are placed and that viewing themis not hampered by the background color of the retaining media. Thedevice is very inexpensive to manufacture, is constructed of very fewparts, is capable of being assembled in few steps, and is designed suchthat it facilitates an automated process.

In connection with describing the needle counter devices, terms such asneedles, blades, sharps, etc. are used with the understanding that theneedle counter device is meant to be used in association with anysurgical device, such as one having a sharp edge or point, which ahealthcare provider may want to keep track of during surgery.

As shown in FIGS. 1-5, the needle counter device 10 includes a base 12and a lid 14 which is pivotably connected to the base 12, such that thedevice 10 can be opened and closed much like a book. The base 12 and lid14 may be of a two piece construction having a snap together assembly,thereby forming one or more hinges 16. Alternatively, the device couldbe constructed of a one piece molded form, connected by means of anintegrally molded living hinge. Regardless, preferably the device 10 isvery inexpensive to manufacture, constructed of very few parts, capableof being assembled in few steps, and designed such that it facilitatesan automated process.

Preferably, the lid 14 provides a generally planar main body portion 18,and an upstanding side wall 20 which is disposed about the periphery ofthe main body portion 18. Latch structure 22 is preferably provided onthe lid 14 and a corresponding hole 24 or other corresponding structureis provided on the base 12, such that the device 10 can be closed, andtends to remain closed unless intentionally opened. The lid 14 ispreferably approximately two thirds of the overall height of the device10 when the device 10 is closed. This provides head space clearanceunder the lid 14 to close upon and contain captured suture needlesretained by the base 12.

As shown in FIG. 2, an adhesive layer 17 with a peel away covering 19may be provided on the outside surface 21 of the lid 14, wherein in use,a user can peel away the covering 19, thereby exposing the adhesivelayer 17, and the adhesive layer 17 can be pressed to a surface, therebysecurably, but removably, mounting the needle counter device 10 to thesurface.

As shown in FIG. 1, a thin layer of adhesive 26 may be provided on theinside 28 of the lid 14, to retain used surgical blades. Alternatively,layer 26 can be a magnetic surface. Additionally, a piece of resilientfoam 29 may be provided on the inside 28 of the lid 14, wherein the foammay be used for temporarily “parking” a suture needle, if desired.Needles having suture attached and still in use may be “parked” into thefoam until time to finish using the suture. As will be described morefully below in connection with FIG. 9, the foam 29 may be provided ashaving an array of holes to facilitate removal of parked needles andscalpel blades.

The base 12 is preferably generally flat, but includes one or aplurality of troughs 30 which are filled with a sticky elastomeric,sharps retaining media or adhesive 32 (due to the need to illustratedetail of the troughs themselves in FIGS. 1, 4 and 5, the adhesive isonly shown in FIGS. 3 and 6). Preferably, the top surface 37 of theadhesive 32 is below the top 39 of each trough 30, as this takes lessmaterial, as well as prevents needle holders and other instruments,sutures, surgical garments and the like from inadvertently coming intocontact with the sticky adhesive.

The troughs 30 may be formed in a variety of cross-sectional shapes.FIGS. 1, 3, 4 and 5 illustrate the troughs 30 as having a V-shapedcross-section, and such shape is preferred. The V-shape trough isconfigured to provide the necessary depth for burying needle tips andsufficient width to provide a reasonable target for users to hit.Nevertheless, other shapes, such as rectangular-shaped cross-sectiontroughs, are entirely possible. While it is possible to provide troughshaving a rectangular-shaped cross-section, that troughs formed in theV-shaped configuration will save considerably in adhesive usage comparedto a same-width rectangular trough design.

Not only are the troughs preferably V-shaped, but preferably each trough30 is relatively narrow having a width (dimension 31 in FIG. 3) of, forexample, 0.150 inches. The depth (dimension 33 in FIG. 3) of each trough30 may be 0.190 inches, while the depth of the adhesive may be, forexample, 0.120 inches. The adhesive may be provided as being even moreshallow, such as shallow as 0.060 inches in height. Not only do narrowtroughs 30 filled to a low level with adhesive 32 cost less tomanufacture, but narrow trough 30 tend to provide that needles insertedinto the adhesive 32 are retained in an upright position by thesidewalls 35 (see FIG. 3) which define each trough 30. If the troughsare provided as being too wide, needles which are inserted into thetroughs may lay over, leaving them harder to count. As a result ofproviding that the troughs are narrow, and the sidewalls 35 closertogether, inserted needles array in a much more vertical and orderlyfashion for quicker recognition and counting. This greatly benefits theuser.

Additionally, due to the troughs 30 being narrow, needles will tend tobe inserted longitudinally instead of transversely into the troughs 30.Hence, guidance of the needles is assisted by the sidewalls 35.Furthermore, the needles can if desired, be pressed downward deeply intothe adhesive 32 instead of being speared into it. This makes theneedle-delivery process very easy.

Regardless of the shape of the troughs 30, preferably the sides 34 ofeach trough 30 are lined with a low interrupted rib or series of spacedapart pickets 36 which serve to prevent an accidentally laid surgicalinstrument from unintentionally contacting the adhesive 32. Preferably,numerical indices 38 are provided alongside each trough 30 to provide aquick visual assist to the counting process at the conclusion of theprocedure. For simplicity, the indices 38 are shown only in FIG. 6.Although the troughs 30 are shown as being vertical relative to theindices 38, they may be provided as being horizontal instead. An exampleof the function of the ribs 36 and numerical indices 38 is illustratedin FIG. 6, wherein a needle 40 has been inserted in the adhesive 32 atlocation 1, and another needle 42 has been laid down upon the adhesiveat location 11. Ideally, the base 12 is of a color, such as red, whichfacilitates good illumination of placed needles to assure easyvisibility for placement and counting at the end of the procedure.Additionally, preferably the adhesive 32 is translucent and provided ina color, such as a honey color, which does not hamper plain viewing ofthe needles.

Preferably, the adhesive 32 which is retained in the troughs 30 is avery high tack, one part, pressure sensitive elastomeric adhesive, andis such that it can be easily delivered to the trough(s) hot, whereuponit quickly sets as it cools. Preferably, the adhesive 32 is clean anddoes not require curing, solvents or fume handling, and is thereforestable and ideal for use in a simple automated in line assembly system.This type of adhesive is well suited to the thick application requiredby the trough design. Preferably, the adhesive is homogeneous. Manydifferent adhesives may be used in association with the presentinvention. The adhesive may be as described in U.S. Pat. No. 5,869,562(see specifically Example 2). U.S. Pat. No. 5,869,562 is herebyincorporated herein by reference in its entirety.

Major benefits of the adhesive-filled trough approach include: 1)Provision of a deep adhesive pool into which a point of a needle can beinserted for capture by means of bonding; 2) Provision of a sufficientadhesive volume to allow large elastic excursions in order to hold ontoand resist removal of any needle the adhesive has become attached to;and 3) Very high initial tack under conditions of minimal needle contactpressure.

The adhesive-filled trough approach is designed to exploit bothmanufacturing and performance benefits of 100% solids content, fume andsolvent free, rapid setting, elastomeric, pressure sensitive adhesive(PSA) materials that can be rapidly applied into deep troughs within theneedle counter. The strength of an adhesive bond is generally understoodto be proportional to the area in contact, thus more area translatesdirectly into a stronger connection. Adhesive thickness has asignificant effect on peel strength of a bond as well. This is due tothe viscoelastic nature of the adhesive. With elastomeric adhesives,thicker bondlines will generally result in higher peel strength.Viscoelastic adhesives also perform better when loaded in a shearcondition than in a peel condition.

The nature of the needle counter design provides for a much largerneedle surface area to be contacted, wetted and gripped by the adhesive.That is because the needle's tip can be immersed deeply into an adhesivefilled trough, wherein adhesive is not only tacky upon its surface, butinternally as well. The entire buried surface of the needle tip istherefore in full contact with tacky adhesive. By comparison, thin filmadhesives applied to foam, membrane or paper substrates of prior artneedle counters provide minimal bondline thickness. In some prior artneedle counter configurations, the adhesive contact area against thepiercing needle is little more than the circumference of the needlemultiplied by the thickness of the adhesive film.

The design also allows the adhesive's viscoelastic properties to befully exploited as part of the retention mechanism by minimizingrestrictions against the adhesive's elongation, should a needle bepulled upon. Elongation for these adhesives can run from 500% to 5000%.This freedom to elongate or stretch in response to loading, resistsneedle pull-out by keeping the adhesive in shear longer, extending thenucleation phase and delaying the onset of bond failure due to peeling.Conversely, the paper or foam substrates of prior art examples, serve torigidize the adhesive film layer. Therefore, the amount of adhesiveavailable to elastically feed or extend itself under load is less sincethis property depends upon adhesive thickness. As a consequence,nucleation peaks early, hastening the onset of bond failure. Under useconditions, with thin rigidized adhesive films, very little traveldistance is permitted by the substrate before elongation and peel limitsare reached. The rigidized adhesive films let go much sooner due totheir inability to delay peel by extending themselves elastically. Thenegative consequence of resistance provided by the rigidizing substrateis that the adhesive is thrown out of shear and into a peel conditionsooner. An additional advantage of the above-described design, using adeep trough of adhesive instead of the conventional thin film adhesive,is the minimization of adverse performance resulting from anydegradation of surface tack due to storage or environmental conditions.

The preferred adhesives for the needle counter device also must besuitable for penetration by any needle type used during a medicalprocedure. Since the variety of needles available is virtuallylimitless, adhesive used in this application must be receptive to verysharp needles ranging from 0.009″ diameter needles half the size of aneyelash, to blunt tipped safety needles 0.062″ in diameter (see, forexample, FIGS. 7 and 8 which illustrate one vendor's needle types). Allneedle types must be accommodated and the insertion force to penetrateinto the adhesive must not be excessive. The penetration requirementsfor these needles mean that the adhesive used in a needle counter deviceshould be soft and stable and not be so tough so as to make needleinsertion difficult. Substrate backing materials of some prior artdevices also tend to reinforce and toughen the immediate underlyingsurface against needle penetration. Very small and blunt safety typeneedles are particularly difficult to insert through this reinforcedunderlayment. The needle counter device design described herein providesa deep homogeneous body of adhesive to receive the needle that is freeof any tough reinforcing surface underlayment and therefore highlyreceptive to all needle types. The ideal adhesive for this applicationpossesses sufficiently low durometer and puncture resistance at itssurface under use conditions, to facilitate easy needle insertion.Experience has shown that adhesives having a durometer ranging from 10to 24 Shore “A”, and preferably in the range of 12 to 20 Shore “A”, workwell in this application.

PRESSURE SENSITIVE ADHESIVES (PSAs). PSAs are generally defined as beingpermanently tacky, requiring no activation by water, solvent or heat.They are inherently soft materials formulated to provide a balance ofadhesive properties and cohesive strength. This balance depends upon theviscoelastic nature of the adhesive as well as the additives used in itsformulation. The primary mode of bonding for a pressure sensitiveadhesive is not chemical or mechanical but rather a polar attraction ofthe adhesive to the substrate. Pressure is required to providesufficient wet-out onto the substrate surface to provide adequateadhesion. Cohesion or internal strength of the adhesive must be highenough to resist creep and shear stresses in the end use application.

With PSAs, surface energy of the intended substrate may dictate the typeof base polymer to be used. Polar polymers such as acrylics adhesiveshave a tendency to adhere best to high surface energy substrates (e.g.,metals, glass, etc.) by virtue of their dipole-dipole interaction and/orhydrogen bonding. Non-polar adhesives tend to adhere to both low (e.g.,plastics and EPDM rubber) and high surface energy substrates.

Hot melt adhesives are composed primarily of thermoplastics or materialswhich appear to be thermoplastic. Elastomer based PSAs typically have asynthetic rubber as the base polymer. Styrene block copolymers orstyrene butadiene rubbers are commonly used as the synthetic base resinin these formulations. Styrenic block copolymer (SBC) is synthesized viaanionic polymerization such as styrene-isoprene (SIS) orstrenebutadiene-styrene (SBS). SBCs offer high cohesive strength similarto that of chemically vulcanized rubbers, yet because the crosslinks inthese polymers are physical rather than chemical, they are reversibleallowing liquid like flow when heated above the glass transitiontemperature (Tg) of the polystyrene molecular endblocks. Some polyamidepolymers are also formulated for high performance hot melt PSAs.Ethylene vinyl acetate (EVA) based adhesives are the most common generalpurpose type of hot melt, but suffer from poor adhesion to low energysubstrates. Other hot melt resin bases are used but are probably not aswell suited to the needs of the needle counter device described hereinas SBC and polyamides. Since a low melt viscosity is required, mostpolymers used as bases for hot melt adhesives are semi-crystalline incharacter.

SBCs are best known for their low temperature flexibility combined withheat resistance and most types are used for pressure sensitiveapplications. Most block copolymers can be mated after the adhesive hascooled. Polyamides are high performance hot melts that are used whenbonds need to resist high temperatures (up to 350F) as well as fuels orsolvents. They are among the strongest hot melt adhesives and can beformulated to be soft and tacky or hard and rigid depending on thepolymer and the resin used.

Typical performance characteristics for SBCs and polyamides are:

-   -   1. High heat resistance.    -   2. Excellent cohesion strength.    -   3. Excellent peel strength.    -   4. High tack—Excellent quick adhesion.    -   5. Low volatile emissions.    -   6. Low post application shrinkage vs. solvent based adhesives.    -   7. Achieve high viscosity very quickly after application.    -   8. High solids content facilitates extremely thick applications.    -   9. Non-polar in nature provides adhesion to both low-surface        energy non-polar substrates and high surface energy polar        substrates.

Tg. Hot melts are characterized by their glass transition temperature(Tg) which is actually a composite of several physical attributes. Itreflects behavior of the adhesive and is a way of understanding themolecular motion that occurs in a polymeric system which is afundamental concern when considering adhesion, cohesion and otherproperties of polymers. At low temperatures, a polymer exists as a solidin which the molecular segments vibrate gently and independently. As thetemperature is increased, a point is reached at which the moleculesuddenly becomes more flexible and mobile. This increased flexibilityoccurs when the molecular vibrations become strong enough to shake theadjacent chain segments apart and allow molecules the freedom to slip byone another. The temperature required for this to occur is known as theglass transition temperature, Tg. It is a transition of the polymer froma glassy to a rubbery state where, as the temperature is raised further,the distance between the molecular segments is increased. This can beobserved as a distinct increase in the slope of the polymer's volume asa function of temperature. The transition reverses upon cooling.

Tg and COHESIVE PROPERTIES. The strength of a crosslinked adhesive atelevated temperatures is very much indicated by its Tg. The Tg should beabove the upper use temperature of the adhesive for good bond strengthand creep resistance. Peel strength however, will be low when Tg isappreciably above the upper use temperature and low temperatureperformance of a relatively high Tg adhesive is limited due tobrittleness. In general, an adhesive's joint strength increases and ismaximized near the Tg.

Tg and PRESSURE SENSITIVE PROPERTIES. Two requirements for PSA is thatit must undergo plastic flow on contact and that it must wet thesubstrate surface. Polymeric materials can only be pressure sensitive(flowable under slight pressure) above its Tg. Thus, most PSA materialshave a Tg near or below room temperature. Having a Tg below roomtemperature does mean that these adhesives will not achieve highcohesive strength since in this rubbery state the molecules are alsomobile enough to flow under load until the bond fails. The ideal Tg istherefore a compromise based on performance needs and is thereforepreferred to be around −29 to −5 degrees C. It can be adjusted throughformulation, but generally, low Tg values ensure very high tack, andmedium Tg gives optimum peel and acceptable cohesive strength.Plasticizers and flexibilizers can be added to lower the Tg of theadhesive polymer by inserting a cohesively weak region of materialbetween the base polymer molecules.

TACKIFYING RESINS. Tackifying resins can also be added to improve the“quick grab” of the adhesive by reducing the viscosity of the polymer togive faster, more complete wetting of the substrate and to raise the Tgof the adhesive (plasticizers accomplish the first objective but not thesecond). Reducing the viscosity makes bond formation easier and raisingthe Tg makes the bond failure more difficult. Wetting is improved whenthe adhesive polymer is fluid and in a molecularly mobile state in whichthe molecular motion allows the adhesive to compete with contaminantsfor attachment to surface sites.

MECHANISMS of TACK. Tack is defined as the property than enables anadhesive to form a bond of measurable strength with the surface ofanother material upon brief contact and under high pressure. Implicit isthat the adhesive separates cleanly from the surface, without anymacroscopic residue. Tack consists of two processes. The first is abonding process resulting from adhesive deformation and flow intocontact with the substrate to allow attachment through polar attraction,after which the second phase, a deformation or debonding process canoccur in which the adhesive separates by peeling from the surface. Tackor resistance to separation of the substrate depends upon:

-   -   1. Ease of deformation, or in our application, penetration of        the adhesive during the bonding stage (this determines the        amount of area of interfacial contact over which the forces of        polar attraction can develop).    -   2. The resistance to separation of contact areas.    -   3. The degree of deformation of the adhesive and, hence, the        amount of energy dissipated as frictional heating during the        debonding process.

Obviously, quantifying the tack property is greatly influenced by theexperimental method and parameters. It depends not only on the nature ofthe PSA and the adherend, but also on pressure and time of contact.Moreover, because the response is a viscoelatic response, thetemperature and the rate of debonding play a key role in the strengthmeasured. In other words, tack is defined by the test used to measureit. So, it is important to know what kind of tests are used, what kindof information is given, and their limits.

Related standards are published by national groups, such as ASTM, and byprofessional associations. Normalized tests are well defined and requireequipment that is easily available. They are a bridge betweenlaboratories, users, distributors, etc. in the industry. Examples ofstandard tack tests include the rolling ball tack test, loop tack test,peel tack test, and probe tack test. Descriptions of such standard testscan be readily found in the industry, and specifically on the Internet.Specifically, descriptions can presently be found, for example, atwww.specialchem4adhesives.com. Equipment for performing these standardtack tests can also easily be found in the industry (i.e., rolling balltack testers, loop tack testers, probe tack testers, etc. are readilyavailable in the marketplace).

BOND FAILURE UNDER LOAD. The phenomena observed during the separation ofan adhered body and a tacky adhesive follows a pattern in which:

-   -   a) Initially, as the adhered body is withdrawn, stress increases        linearly with displacement of the body.    -   b) Then, stress begins to increase at a non-linear rate due to        nucleation (the appearance of voids at the interface).    -   c) The force reaches a maximum when nucleation stops.    -   d) Then a decrease in stress occurs as cavities, perpendicular        to the interface start to grow.    -   e) Debonding then begins to occur as either, 1) the voids grow        until coalescence occurs and stress decreases to zero (adhesion        failure), or 2) cavities grow to a critical size, fibrillation        appears and the fibrils lead to either adhesion failure or a        cohesive failure within the adhesive.

MEASUREMENT of TACK. Tack is defined by the test used to measure it. Abrief explanation of common measuring methods relevant to the presentapplication are discussed below:

1. ROLLING BALL TACK TEST (RBT). This simple, frequently used test isone of the oldest. It gives a good idea of the adhesive behavior and isreadily understood. It provides a quick comparison of high-tackadhesives. The distance a ball rolls down a ramp is inverselyproportional to tackyness; the greater the distance, the less tacky theadhesive.

In the procedure, a rolling object (typically a steel ball) is placed atthe top of an inclined track pursued by a horizontal, upward-facingadhesive. The ball is allowed to roll down the track and the relevantmeasurement is the distance the ball travels along the adhesive surface.The test method is outlined in ASTM-D 3121.

2. PROBE TACK TEST. Analogous to pressing a thumb into the adhesive andwithdrawing it, this test allows more precise and reproducible results.Mechanical probe tack testers bring a probe (ball or cylinder of variousmaterials) into contact at a controlled rate and pressure, wait a givendelay, and measure the force needed to pull away at a specified rate.The test method is based upon ASTM-D 2979-00, based on the Polyken ProbeTack test.

Other tests commonly associated with hot melt PSAs include:

-   -   VISCOSITY, to determine the molten viscosity of the hot melt        adhesive at a specified temperature. ASTM-D 3236-88    -   RING and BALL SOFTENING POINT (RBSP), to determine the softening        point of a hot melt adhesive. ASTM-E 28-67    -   SHEAR ADHESION FAILURE TEMPERATURE (SAFT), to test heat        resistance of hot melt adhesives in the shear mode under a        predetermined load and constantly rising temperature. ASTM-D        4498-85.    -   180 DEGREE PEEL, to test adhesion of pressure sensitive        adhesives to stainless steel panels or high density polyethylene        (HDPE) panels. ASTM-D 3330.    -   STATIC SHEAR TIME TO FAILURE, to test creep resistance of hot        melt adhesives in the shear mode. ASTM-D 2294 and PSTC-7.    -   MELT FLOW INDEX (MFI), to determine the relative viscosity of        thermoplastic polymers (related to molecular weight and        structure of a polymer). ASTM-D 1238-9

Desirable physical properties for the adhesive used in connection withthe needle counter device shown in FIGS. 1-6 and described hereinaboveare:

-   -   1. Type: Hot Melt PSA, high tack    -   2. Ingredients: Approved under Fed. Reg. 21 CFR 175.105    -   3. Ring & Ball SP: 180° F. (82° C.) to 212° F. (100° C.)    -   4. Withstand Sterilization: ETO, Gamma, E-Beam    -   5. Color: Light for visualization of needle    -   6. SAFT degrees F.: 151F+/−2F (Static Adhesion Failure Test)    -   7. 180 degree peel lbs./inch=/>3.2    -   8. Looptack oz./inch=/>86    -   7. Polar Nature of Polymer: Non-Polar preferred, polar possible    -   8. Viscosity: (Brookfield RVT)        -   300° F. (149° C.) 10,000 (cP)-16,000 (cP)        -   350° F. (177° C.) 3,600 (cP)-6,600 (cP)    -   9. Tg: −20° F. (−29° C.) to 23° F. (−5° C.)    -   10. Durometer Range: 12 to 20 Shore “A”    -   11. Rolling Ball Tack: N.A.    -   12. Probe Tack: N.A.    -   13. Application Temp.: <375° F. (177° C.)

Various surgical blade types are often used during a surgical procedure.Blades of differing styles may be periodically exchanged on the scalpelhandle, the removed blade being set aside for reuse later. In theseinstances, the thin adhesive layer 26 within the needle counter lid 14would not be suitable for temporary parking. Layer 26 can be provided asbeing a magnetic sheet. However, while magnetic force tends to retainthe blades well enough, the thin blades prove hard to pick up off such amagnetic surface.

As mentioned above, the foam pad 29 is provided on the inside 28 of thelid 14 may be provided as having holes. FIG. 9 illustrates the situationwhere foam pad 29 a covers at least half of the lid surface and includesa plurality of through holes 52 arrayed in a grid pattern. Specifically,the pad 29 a may be approximately 3/16″ thick and have ¼″ through holes52 arrayed in a 0.5″×0.5″ grid pattern (wherein the center of each holeis 0.500 inches apart) over the entire pad area. The pad's surface,which is softer than a magnet's, prevents damage to the fragile cuttingedges of scalpel blades and provides sufficient grip to keep blades fromsliding about. Blades laid on the perforated pad surface will inevitablybridge one or more holes. The location of this bridging provides a placeto position a forceps tip under the blade to retrieve it forreinstallation on a scalpel handle when required. Should a hole not behandy, the compliance of the foam pad allows compression by the forcepstip in order to slip it beneath a blade. When a foam pad such as this isutilized, retention of the blades for disposal is accomplished by eithersinking the scalpel blade tip in the adhesive filled trough ordelivering it to a portion of the lid not covered by the foam and havinga light coating of a sticky adhesive material 26 instead. This foamcould provide double duty, functioning as a needle parking station, aswell as a parking station for scalpel blades.

FIGS. 10-14 illustrate a needle counter device 10 a which is inaccordance with an alternative embodiment of the present invention. Theneedle counter device 10 a shown in FIGS. 10-14 is much the same as theneedle counter device 10 shown in FIGS. 1-6 and 9, but for the latchmechanism 15 a. For example, much like the needle counter device 10described in detail hereinabove, the needle counter device 10 apreferably has adhesive-filled troughs 30 a with associated needlecounter indicia (indicated with dots 38 a in FIG. 10, but see FIG. 6 andassociated description for detail regarding the indicia) on its base 12a, and a thin layer of adhesive or a thin magnetic surface 26 a may beprovided on the inside 28 a of the lid 14 a, to retain used surgicalblades. The lid 14 a and base 12 a are preferably connected with a hinge16 a; however, they may be integral with each other and have a livinghinge therebetween. Additionally, much like the needle counter device10, the needle counter device 10 a may have a piece of resilient foam 29b on the inside 28 a of the lid 14 a, wherein the foam may be used fortemporarily “parking” a suture needle, if desired. The foam 29 b may ormay not have through holes, such as is shown in FIG. 9 (see foam 29 a inFIG. 9). Also, an adhesive layer 17 a with a peel away covering 19 a maybe provided on the outside surface 21 a of the lid 14 a. All this isdescribed in detail hereinabove in connection with needle counter device10.

As shown in FIG. 10, the base 12 a includes a raised lip 102. As shownin FIGS. 11, 13 and 14, when the lid 14 a is closed and latched, a lip104 of the lid 14 a seats against a surface plane 106 formed upon thebase 12 a. The base 12 a is preferably planar, and the raised lip 102extends upward from the planar surface 106 of the base 12 a, and servesto: 1) locate the lid 14 a when the lid 14 a is closed, as shown in FIG.11; 2) provide structural support for the thin lid 14 a againstdislodgement by transferring that load to the base 12 a when the closeddevice 10 a receives an impact, such as if dropped; 3) provide atortuous path against the escape of a contaminate needle or sharpcontained within the closed structure; and 4) prevent damaging relativemotion between the latch 15 a and hinge 16 a due to side impact byresolving the impact loads within the lid 14 a and base 12 a structuresthemselves.

With regard to the latch mechanism 15 a, as shown in FIGS. 10-14, thelatch mechanism 15 a consists of a latch member 22 a and a correspondinghole 24 a in the base 12 a, and the latch member 22 a is integrated intothe edge 23 a of the lid 14 a. As shown in FIG. 10, the side 25 a of thelid 14 a includes a surface 27 a, and the latch member 22 a extendsfrom, and is effectively integral with, this surface 27 a and has a hookportion 129 a on its end 31 a. In other words, the latch mechanism 15 acomprises an integral barb 22 a which depends directly from a wall 27 aof the lid 14 a and penetrates the hole 24 a in the base 12 a, therebysecuring the device 10 a in a closed condition. The latch member 22 a isinsertable and removeable from the hole 24 a such that the device 10 acan be secured in the closed condition, as shown in FIGS. 11-14, andtends to remain closed unless intentionally opened. More specifically,the base 12 a constitutes a planar surface 106 having a hole 24 a in theplanar surface to receive the latch member 22 a. The latch mechanism 15a is configured to provide that the latch member 22 a need not go intoor require a bail with which to mate. Compared to the latch mechanism(i.e., the latch 22 and hole 24) of the needle counter device 10 shownin FIGS. 1-6 and 9, the latch mechanism 15 a of the needle counterdevice 10 a shown in FIGS. 10-14, due to the latch member 22 a beingintegrated into the edge 23 a of the lid 14 a, simplifies manufacturing,as well as increases resistance to deflection and spreads the openingload (i.e., the load used to unhook the latch member 22 a from the hole24 a) into a whole side 25 a of the device 10 a instead of having theload be concentrated at a narrow portion.

As discussed hereinabove, the latch mechanism 15 a shown in FIGS. 10-14can be implemented in connection with a needle counter device whichutilizes an adhesive disposed in one or more troughs (see FIGS. 1-6 and9 and associated description hereinabove). Alternatively, the latchmechanism 15 a can be implemented in connection with a more conventionalneedle counter device, such as one which does not include an adhesivedisposed in one or more troughs.

The hinge mechanism 16, 16 a (with regard to either needle counterdevice 10, 10 a) preferably consists of a plurality of hinges (such as apair as shown in FIGS. 1, 2, 4, 5 and 10), each of which is identicaland may be provided as shown in FIG. 15. As shown in FIG. 15, each mayconstitute a “U” shaped hinge finger 110 provided on the base 12, 12 aand having a cleat 112 which effectively engages and retains acomplimentary hinge pin 114 which is provided on the lid 14, 14 a,disposed between two walls 116, thereby retaining the hinge form.Alternatively, some other appropriate hinge structure can be used inassociation with the needle counter devices 10, 10 a.

While embodiments of the present invention are shown and described, itis envisioned that those skilled in the art may devise variousmodifications of the present invention without departing from the spiritand scope of the present disclosure.

1. A needle retaining device comprising: a lid; a base integral with orconnected to the lid and configured to retain needles, wherein an edgeof the lid has a latch integral therewith, wherein the latch isreceivable in a corresponding hole in the base, thereby locking theneedle retaining device in a closed condition.
 2. A needle retainingdevice as recited in claim 1, wherein said lid includes a lip and saidbase includes a planar surface, wherein said lip of said lid seatsagainst the planar surface of said base when said needle retainingdevice is closed, wherein there is at least one trough provided in saidplanar surface of said base; and a cohesive material disposed in thetrough, wherein said cohesive material is configured to bond to a needleand thereafter resist withdrawal of said needle.
 3. A needle retainingdevice as recited in claim 1, wherein said hole is provided in a planarsurface of said base, and, wherein there is at least one trough providedin said planar surface of said base; and a cohesive material disposed inthe trough, wherein said cohesive material is configured to bond to aneedle and thereafter resist withdrawal of said needle.
 4. A needleretaining device as recited in claim 1, wherein the base includes araised lip which extends from a planar surface of the base, said raisedlip configured to serve at least one of the following functions: locatethe lid when the needle retaining device is closed; provide structuralsupport for the lid against dislodgement by transferring a load to thebase when the needle retaining device is closed and receives an impact;provide a tortuous path against escape of a contaminate needle or sharpcontained within the needle retaining device when the needle retainingdevice is closed; and prevent damaging relative motion between the latchand a hinge of the needle retaining device due to side impact byresolving impact loads within the lid and base.
 5. A needle retainingdevice as recited in claim 1, wherein the lid and the base are twodifferent sized and shaped pieces which are configured to performdifferent functions.
 6. A needle retaining device as recited in claim 1,wherein the base includes a surface, at least one trough provided insaid surface; and a cohesive material disposed in the trough, whereinsaid cohesive material is configured to bond to a needle and thereafterresist withdrawal of said needle.
 7. A needle retaining device asrecited in claim 6, wherein said cohesive material is configured suchthat the needle is easier to stick in the cohesive material than it isto pull the needle out of the cohesive material.
 8. A needle retainingdevice as recited in claim 6, wherein said needle retaining deviceincludes a plurality of troughs provided in said surface.
 9. A needleretaining device as recited in claim 6, wherein said trough is V-shaped.10. A needle retaining device as recited in claim 6, wherein said troughsidewalls are arrayed with an included angle between the opposing faces.11. A needle retaining device as recited in claim 10, wherein sidewallswhich define said trough generally prevent the needle from falling over.12. A needle retaining device as recited in claim 6, wherein saidcohesive material comprises a hot melt cohesive material.
 13. A needleretaining device as recited in claim 6, wherein the lid is at least oneof connected and integral with said base, said lid being pivotablerelative to said base, wherein said needle retaining device is openableand closeable.
 14. A needle retaining device as recited in claim 13,wherein the needle retaining device is configured such that once thedevice is closed, the device tends to remain closed unless intentionallyopened.
 15. A needle retaining device as recited in claim 14, furthercomprising a latch structure which is configured to secure said lid andsaid base relative to each other.
 16. A needle retaining device asrecited in claim 13, further comprising a layer of cohesive materialdisposed on an inside surface of said lid.
 17. A needle retaining deviceas recited in claim 13, further comprising a piece of resilient foamdisposed on an inside surface of said lid.
 18. A needle retaining deviceas recited in claim 13, further comprising a layer of cohesive materialdisposed on an inside surface of said lid, and a piece of resilient foamdisposed on the inside surface of said lid, proximate said layer ofcohesive material.
 19. A needle retaining device as recited in claim 13,further comprising a magnetic surface disposed on an inside surface ofsaid lid.
 20. A needle retaining device as recited in claim 6, whereinsides of the trough are lined with structure which is configured toprevent an accidentally laid needle from unintentionally contacting thecohesive material.
 21. A needle retaining device as recited in claim 20,wherein said structure which is configured to prevent an accidentallylaid needle from unintentionally contacting the cohesive materialcomprises pickets.
 22. A needle retaining device as recited in claim 6,further comprising numerical indicia disposed on said surface, proximatesaid trough, said numerical indicia configured to provide a visualcounting assist of needles retained by said cohesive material.
 23. Aneedle retaining device as recited in claim 6, wherein said cohesivematerial comprises an adhesive.
 24. A needle retaining device as recitedin claim 6, wherein said cohesive material is translucent.
 25. A needleretaining device as recited in claim 6, wherein said cohesive materialis homogeneous.
 26. A needle retaining device as recited in claim 6,wherein said adhesive is at least 0.060 inches deep.
 27. A needleretaining device as recited in claim 13, further comprising a hingemechanism configured to provide that the lid is pivotable relative tothe base, wherein the hinge mechanism comprises a “U” shaped hingemember having a cleat configured to retain a complimentary hinge pin.28. A needle retaining device as recited in claim 27, wherein the “U”shaped hinge member is provided on the base, and the complimentary hingepin is provided on the lid.
 29. A needle retaining device as recited inclaim 1, wherein the latch comprises an integral barb which dependsdirectly from a wall of the lid and penetrates the hole in the base,thereby securing the device in a closed condition.